<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title></title>
		<style type="text/css">
			.father{
				width: 200px;
				height: 200px;
		
			}
		</style>
	</head>
	<body>
		<div class="father" id="son"></div>
		<script src="js/jquery-2.1.0.js" type="text/javascript"></script>
		<script>
			$(".father").css("background","yellow");
			$('#son').css("border","3px solid red");
		</script>
	</body>
</html>
